﻿<!DOCTYPE html>
<html>
<head>
  <title>Minimal Image Blob and Download</title>
  <!-- Copyright 1998-2021 by Northwoods Software Corporation. -->
  <meta name="description" content="Minimal, showing image Blob creation and download with Diagram.makeImageData." />
  <meta name="viewport" content="width=device-width, initial-scale=1">

  <script src="../release/go.js"></script>
  <script src="../assets/js/goSamples.js"></script>  <!-- this is only for the GoJS Samples framework -->
  <script id="code">
    function init() {
      if (window.goSamples) goSamples();  // init for these samples -- you don't need to call this

      var $ = go.GraphObject.make;  // for conciseness in defining templates

      myDiagram = $(go.Diagram, "myDiagramDiv",  // create a Diagram for the DIV HTML element
        {
          "undoManager.isEnabled": true  // enable undo & redo
        });

      // define a simple Node template
      myDiagram.nodeTemplate =
        $(go.Node, "Auto",  // the Shape will go around the TextBlock
          $(go.Shape, "RoundedRectangle", { strokeWidth: 0 },
            // Shape.fill is bound to Node.data.color
            new go.Binding("fill", "color")),
          $(go.TextBlock,
            { margin: 8 },  // some room around the text
            // TextBlock.text is bound to Node.data.key
            new go.Binding("text", "key"))
        );

      // but use the default Link template, by not setting Diagram.linkTemplate

      // create the model data that will be represented by Nodes and Links
      myDiagram.model = new go.GraphLinksModel(
        [
          { key: "Alpha", color: "lightblue" },
          { key: "Beta", color: "orange" },
          { key: "Gamma", color: "lightgreen" },
          { key: "Delta", color: "pink" }
        ],
        [
          { from: "Alpha", to: "Beta" },
          { from: "Alpha", to: "Gamma" },
          { from: "Beta", to: "Beta" },
          { from: "Gamma", to: "Delta" },
          { from: "Delta", to: "Alpha" }
        ]);

      document.getElementById("blobButton").addEventListener("click", makeBlob);
    }

    // When the blob is complete, make an anchor tag for it and use the tag to initiate a download
    // Works in Chrome, Firefox, Safari, Edge, IE11
    function myCallback(blob) {
      var url = window.URL.createObjectURL(blob);
      var filename = "myBlobFile.png";

      var a = document.createElement("a");
      a.style = "display: none";
      a.href = url;
      a.download = filename;

      // IE 11
      if (window.navigator.msSaveBlob !== undefined) {
        window.navigator.msSaveBlob(blob, filename);
        return;
      }

      document.body.appendChild(a);
      requestAnimationFrame(function() {
        a.click();
        window.URL.revokeObjectURL(url);
        document.body.removeChild(a);
      });
    }

    function makeBlob() {
      var blob = myDiagram.makeImageData({ background: "white", returnType: "blob", callback: myCallback });
    }
  </script>
</head>
<body onload="init()">
<div id="sample">
  <!-- The DIV for the Diagram needs an explicit size or else we won't see anything.
       This also adds a border to help see the edges of the viewport. -->
  <div id="myDiagramDiv" style="border: solid 1px black; width:400px; height:400px"></div>
  <button id="blobButton">Make Blob and Download</button>
  <p>
    This sample shows how to use <a>Diagram.makeImageData</a> with the <code>returnType: "blob"</code> option
    and the necessary <code>callback</code> option.  It also shows how to download a file that the page has generated.
  </p>
</div>
</body>
</html>
